Dual-speed drive for phonographs and sound recording machines



20, 1949 F. w. BOWEN 2,491,949

DUAL-SPEED DRIVE FOR PHONOGHAPHS AND SOUND RECORDING MACHINES Filed Oct. 2, 1947 111 l 7 IN TOR- m Fe/ix' W Bowel1 6a I v BY 7a 1};/. ig??? Patented Dec. 20, 1949 DUAL-SPEED DRIW E FOR -PHONOGRA'PHS AND-SOUND RECORDING- MACHINES re-ax "W. Bowen, Chevy Chase, Md, '"assignor to Bowen and =Gompa'ny, Inc., "a corporation of Delaware 'Application October 2, 1947, Serial No. 777,545

(CUM- 721) This invention relates to "a 'dualspeed drive "suitable for phonographs and "sound recording machines.

-An' objector the invention'is'to deviseawa'rrangement for'dri'ving "the turntable of asound machine "at-two different spee'ds and toproviiie "a simple control arrangement for quickly changing from one speeclto theother.

"A more specific object'of the invention isto-"devise an arrangement for "driving the turntable from two separate motors, and to'provide' a'simple control system having a single 1 control member movable between two operative positions "to"co'n- 'nect cme or -the other of -the two motorsin driving relation with *the turntable. The control member is also arranged to-loperatea double-pole switch to energize the motor which is in operative engagement with the turntable and to-open "the circuitofthe other 'motor.

One embod-iment of the invention: is illustratetl in the accompanying drawing in which 'Fi'gure 1 is the plan view of the dual motor drive,' the the dual motor'drive and which-is 'toibe secured to a horizontal board or'wall located at or near the top of a suitable enclosing cabinet not-shown. At the center ofth-e plate i a rotary spindl'ei i's mounted in a suitable bearing 3 carried my the plate, and the'turntable4 (shown in dotted: lines) is "carried by the spindle 2 and isl provided'with a depending cylindrical-rim 4a.

On opposite sides of the spindle Z are mounteH two independent motor drives "employing =motors of the synchronous type. Since'these twozmotor drives are duplicates-"except for the diameter-sol" the driving ends of the two-motorshaftafonlyone motor drive will be described, and the second motor'drive will'beindicated on the drawing by the same reference numeralsflprimed.

Each motor drive isconstruc'te'd'as a unit and is supported on the plate 1 by suitable resilient supports to be described. The driveunitincludes a supportingplate 5 arranged above the plate I and. supported'at"three"difierent"points by resilient grommets 6a, 6b and (to. These rommets are preferably formed of'rub'ber and pass through holes formed in the plate lln themanner in'dicated at 6a in Figure 3. Suitable: screws 'la, 119 and 10. pass upwardly through the grommetsdirt,

52 6b 'an'd 'B and have threaded engagement with thei'plate "5. 'Theholes'in plate 5 Which'the grommets arelOcate'd are or smaller diameter than the eiiternal diameterof the "grommets, and

the plate I 'is positioned within circulartgrooves formed in thegrommets atapoirit intermediate the ends thereof asfishowni'n 'Fi'gure 3. .Annelec- 'tric motor is located below the plate 'i an'dds suspendedlrom thetplateB by suitable suspension rods BJOne-of whichis shownlin"Figure'2. "These rods pass through enlargedholes inplate'l and are'attached at their lower ends'to the laminated field 's'truct'urefi or the motorhaving anenergi-zin'g'windihg ill. 'The armature ofthemotoris journall'ed in suitable bearing bells i i mountedon pposite sides 'Of larriinated'field'9, and the armature li'a'sa vertical'shaft ['2 which eXtends upwardlythroughahol'e inplate l and'through'an opening-5am plateb. The lower end of "the motor shaft is provided"'with ayentilatingfa'n |'3"for blowing air upwardly against the motor.

Po'sitioned'ontop 'of"plate"5 is plate M of generally triangular shape, although it may be "of f a difierent shape. An idler wheel l'5'is'journalled secured in a hole in the plate 1'4 and'eiitending through anenlarged" hole in theplateB as shown in Figure 3. The-washer Mbis carried 'onthe low r end of the sleeve Ma below the plate Sand holdsth'e plate M infpos ition on the plate SWh'ile permitting'sliding"of thep-la'te i 4 over th'e's'urface oftheplate 'iiin all di1'ections,limited "only "by the'size'of the hole'implateii. *A" depending finger -i4c is provided near "the inner corner "of the plate M, Figure 1. This finger extends downwardly through an elongated slot '61) formed in plateii. This finger provides api'vot pointfor the plate 5, and this point is slida'ble' along the ails of the'slot 5b, thus-permitting the idler wheel f5 to move generally radially of "theplatel.

The wheel i5 is provided with a rim l'li'a" formed of rubberor'other suitable "material toincrease the friction of the wheel "against engaging- "surfaces.

A tension spring 56 is "secured between the lower edge of plate i4 inFigurel and'a pointoh the plate 5 to *move the plate i4 so that the rim lid of the wheel I 5 -'engages the motorshaft I 2 and also tends to engage the cylindrical-rim lw of the turntable *4, unlessm'ovement of" the plate M isrestrained. "Byreferring to Figure lit willbe seen "that the wheel i 5'- of the right hand motor drive is -in engagement with the "motor shaft f2 and with the turntable rim 4a, but the wheel f5 of the left hand motor drive is held out-dietigagement with the rim do by an arrangement now to be described.

Control slide or bar I! provided with a control knob Ila is'arranged above the plate I and extends diametrically across the plate as shown in Figure 1. The spindle 2 and the bearing 3 pass through an enlarged hole l'lb formed in an enlarged portion of the bar I1, thereby permitting limited movement of the bar H in the direction of its axis. The bar I1 is suspended from the two plates 5 and 5 by an arrangement permitting limited movement of the bar along the axis thereof, such as by means of two screws 18 and I8 passing upwardly through elongated slots He and Ho formed in the bar I! and having threaded engagement with the plates 5 and 5. The bar I1 is provided with an arm I'Id extending to one side and arranged to engage the depending finger I40 when moved in the direction of the arrow 18, and

to thereby move the plate M to disengage the wheel l5 from the turntable rim 4a. A similar arm i'ld extends laterally from the bar I! in the opposite direction and is arranged to engage the depending finger 14c and move the wheel l5.

I5 from the turntable rim 4a, and the arm 11d I moves away from the finger I40 and. allows the spring Hi to move the wheel l5 into engagement with the rim la, In this position of the bar I! the right hand motor unit is connected in driving relation with the turntable, and the diameter of the motor shaft 12' is of the proper value for driving the turntable at a speed of 78 revolutions per minute. When the bar I! is shifted in the opposite direction, the right hand motor unit is disconnected from the turntable and the left hand motor unit is placed in operative connection with the turntable, and the diameter of shaft I2 is of a proper value to drive the turntable at 33 revolutions per minute.

It is not desirable to have both motors operative simultaneously, and for this purpose the control bar I! is provided with a bifurcated arm lie extending to one side thereof and engaging the operating lever W of an electric switch mounted on the plate i. The switch 20 may be of any suitable double-pole construction for closing the circuit to one motor in one position and opening the circuit of the other motor. A suitable construction is illustrated diagrammatically in Figure 2 in which operation of the switch arm [9 to the right in Figure 1 serves to shift the bridging element a to bridge one pair of contacts in the circuit of the right hand motor and to bridge a pair of contacts in the circuit of the left hand motor when the bar [1 is moved to the left. It will be understood that the motor units are energized from a suitable alternating current circuit represented at 2!. Since the two motors are of the synchronous type, the proper speed of the turntable is maintained at all times without the necessity for adjustment.

From the foregoing it will be seen that friction Wheels l5 and i5 constitute movable transmission elements for connecting and disconnecting the motors to the turntable. The bar I! constitutes a single control member for simultaneously operating these elements in opposite directions to engage one driving connection and disengage the other.

I claim:

1. A dual-speed drive comprising, in combination, a base plate having a rotatable spindle mounted at the center thereof, a pair of motors mounted on said plate on opposite sides of said spindle, a pair of friction wheels, a pair of mounts for said wheels mounted on said plate on opposite sides of said spindle and arranged for limited sliding movement outwardly with respect to said spindle, spring means acting on each Wheel mount urging said wheels into engagement with the respective shafts of said motors and tending to shift said wheels outwardly with respect to said spindle, and a common control member extending between said wheel mounts and being movable in one direction to shift one wheel mount inwardly,

- and movable in the opposite direction to shift the other Wheel mount inwardly.

2.'A dual-speed drive for the turntable of a sound machine comprising, in combination, a supporting base having a spindle rotatably mounted thereon for supporting said turntable, a pair of constant speed drive shafts mounted upon said base at diametrically opposite points with respect to said spindle and positioned inwardly from the rim of said turntable, a driving connection from one of said drive shafts to the rim of said turntable for driving said turntable at one speed, a second driving connection from the second shaft for driving said turntable at a different speed, each of said driving connections including a friction Wheel interposed between the respective driving shaft and the rim of said turntable, each wheel being mounted for movement radially of said turntable, spring means normally urging each friction Wheel into engagement with the respective driving shaft and with the rim of the turntable, and a common control member connected with said friction wheels and being movable in one direction to disengage one friction wheel from said turntable and being movable in the opposite direction to disengage the other friction wheel from said turntable.

3. A dual-speed drive for the turntable of. a sound machine comprising, in combination, a supporting base having a spindle rotatably mounted thereon for supporting said turntable, a pair of constant. speed drive shafts mounted upon said base at diametrically opposite points with respect to said spindle and positioned inwardly from the rim of said turntable, a pair of friction wheels interposed between said drive shafts and the rim of said turntable, said wheels being arranged on opposite sides of the diametrica1 line passing through the axes of said shafts and each wheel being mounted for movement radially of said turntable, spring means normally urging each friction wheel into engagement with the rim of the turntable, and a common control member connected with said friction wheels and being movable in one direction to disengage one friction wheel from said turntable and being movable in the opposite direction to disengage the other friction wheel from said turntable.

FELIX W. BOWVEN.

REFERENCES CITED The following references are of record in the file of this patent: I

UNITED STATES PATENTS Number, Name Date 1,370,899 Molesworth Mar. 8, 1921 2,097,071 Lichten Oct. 26, 1937 2,325,602 Gay Aug. 3, 1943 2,392,193 Schneider Jan. 1, 1946 

